Glass article

ABSTRACT

A glass article contains: in mol %, more than 0% to 70% of La2O3, 0% to 80% of B2O3, 0% to 40% of SiO2, 0% to 80% of B2O3+Al2O3+SiO2, 0% to 85% of Gd2O3+Ga2O3+Y2O3+Yb2O3+ZrO2+TiO2+Nb2O5+Ta2O5+WO3, 0% to 15% of MgO+CaO+SrO+BaO, 0% to 35% of ZnO, and more than 0% to 5% of CuO.

TECHNICAL FIELD

The present invention relates to a glass article suitable for decorationpurposes, such as a ring, a pendant, an earring, or a bracelet.

BACKGROUND ART

Paraiba Tourmaline is known as a jewel with vivid neon blue or neongreen (see, for example, non-Patent literature 1). Neon blue or neongreen of Paraiba Tourmaline is color development by copper ions andmanganese ions, and the color tone changes due to the content of theseions. At present, a jewel having a similar color tone is not known.

CITATION LIST Patent Literature

-   Non-Patent Literature 1: Gems & Gemology, Fall 1990, Vol. 26, No. 3,    189-204

SUMMARY OF INVENTION Technical Problem

Paraiba Tourmaline with vivid neon blue or neon green has very littleproduction volume and has a problem of being easy to crack because ithas many inclusions and cracks. There is Tourmaline, another ore, havinga color tone close to that of Paraiba Tourmaline, but since therefractive index is low as 1.62 to 1.64, sufficient brilliance is notobtained when used as a decoration.

In view of the above, an object of the present invention provides anovel article excellent in brilliance and having a color tone of vividneon blue or neon green.

Solution to Problem

As a result of diligent studies, the present inventors have found thatthe above problem can be solved with a glass article having acomposition containing CuO with a base glass containing La₂O₃ as anessential component.

That is, a glass article according to the present invention contains: inmol %, more than 0% to 70% of La₂O₃, 0% to 80% of B₂O₃, 0% to 40% ofSiO₂, 0% to 80% of B₂O₃+Al₂O₃+SiO₂, 0% to 85% ofGd₂O₃+Ga₂O₃+Y₂O₃+Yb₂O₃+ZrO₂+TiO₂+Nb₂O₅+Ta₂O₅+WO₃, 0% to 15% ofMgO+CaO+SrO+BaO, 0% to 35% of ZnO, and more than 0% to 5% of CuO. In thepresent description, “x+y+ . . . ” means a total amount of components.

The glass article according to the present invention preferably containsB₂O₃+Al₂O₃+SiO₂ in an amount of more than 0% to 80% in mol %.

The glass article according to the present invention preferably containsGd₂O₃+Ga₂O₃+Y₂O₃+Yb₂O₃+ZrO₂+TiO₂+Nb₂O₅+Ta₂O₅+WO₃ in an amount of morethan 0% to 85% in mol %.

The glass article according to the present invention may further containa coloring component composed of an oxide of V, Cr, Mn, Fe, Co, Ni, Mo,Ru, Ce, Pr or Er in an amount of 0% to 20% in mol %. Accordingly, thecolor tone of the glass article can be arranged in various ways.

The glass article according to the present invention preferably has arefractive index of 1.7 or more. When the refractive index of the glassarticle is large, the difference in refractive index between the insideand the outside (atmosphere) of the glass article is large, and light iseasily reflected inside the glass article. As a result, it is easy toobtain sufficient brilliance as a glass article.

The glass article according to the present invention preferably has anAbbe number of 50 or less. When the Abbe number of the glass article issmall, the dispersion is high, and rainbow-colored brilliance calledfire is likely to exhibit.

The glass article according to the present invention is preferablysubjected to chamfering. Accordingly, light is easily reflected insidethe glass article, and it is possible to enhance the brilliance.

The glass article according to the present invention is preferably usedfor decoration.

The glass article according to the present invention is preferably anartificial jewel.

A decoration according to the present invention includes the above glassarticle.

Advantageous Effects of Invention

According to the present invention, it is possible to provide a glassarticle excellent in brilliance and fire and having a color tone ofvivid neon blue or neon green.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a plane photograph showing samples Nos. 8, 9 and 39 inExamples.

DESCRIPTION OF EMBODIMENTS

A glass article according to the present invention contains: in mol %,more than 0% to 70% of La₂O₃, 0% to 80% of B₂O₃, 0% to 40% of SiO₂, 0%to 80% of B₂O₃+Al₂O₃+SiO₂, 0% to 85% ofGd₂O₃+Ga₂O₃+Y₂O₃+Yb₂O₃+ZrO₂+TiO₂+Nb₂O₅+Ta₂O₅+WO₃, 0% to 15% ofMgO+CaO+SrO+BaO, 0% to 35% of ZnO, and more than 0% to 5% of CuO. Thereason for limiting the glass composition in this way will be describedbelow. In the following description of the content of each component,“%” means “mol %” unless otherwise specified.

La₂O₃ is a component that forms a network of a glass and is a componentthat increases the refractive index without lowering the transmittance.In addition, La₂O₃ also has an effect of improving weather resistance.The content of La₂O₃ is preferably more than 0% to 70%, 5% to 68%, 8% to65%, 14% to 63%, and particularly preferably 20% to 63%. When thecontent of La₂O₃ is too small, it is difficult to obtain the aboveeffects. On the other hand, when the content of La₂O₃ is too large,vitrification is difficult.

B₂O₃ is a component that forms a network of a glass and expands thevitrification range. The content of B₂O₃ is preferably 0% to 80%, 3% to70%, 5% to 50%, and particularly preferably 10% to 40%. When the contentof B₂O₃ is too large, the refractive index decreases, making itdifficult to obtain desired optical properties.

SiO₂ is a component that forms a network of a glass and expands thevitrification range. The content of SiO₂ is preferably 0% to 40%, 1% to30%, and particularly preferably 3% to 20%. When the content of SiO₂ istoo large, the refractive index decreases, making it difficult to obtaindesired optical properties.

In order to facilitate vitrification, it is preferable to adjust thecontent of B₂O₃+Al₂O₃+SiO₂. The content of B₂O₃+Al₂O₃+SiO₂ is preferably0% or more, more than 0%, 0.1% or more, 3% or more, and particularlypreferably 5% or more. However, when the content of B₂O₃+Al₂O₃+SiO₂ istoo large, the refractive index decreases, making it difficult to obtaindesired optical properties, and is thus preferably 80% or less, 75% orless, and particularly preferably 70% or less.

Al₂O₃ is a component that forms a network of a glass and expands thevitrification range. However, when the content of Al₂O₃ is too large,the refractive index decreases, making it difficult to obtain desiredoptical properties. Therefore, the content of Al₂O₃ is preferably 0% to80%, 1% to 75%, and particularly preferably 3% to 70%.

Gd₂O₃, Ga₂O₃, Y₂O₃, Yb₂O₃, ZrO₂, TiO₂, Nb₂O₅, Ta₂O₅, and WO₃ arecomponents that increase the refractive index, reduce the Abbe number toincrease the dispersion, and expand the vitrification range. The contentof Gd₂O₃+Ga₂O₃+Y₂O₃+Yb₂O₃+ZrO₂+TiO₂+Nb₂O₅+Ta₂O₅+WO₃ is preferably 0% to85%, more than 0% to 85%, 1% to 80%, 5% to 75%, and particularlypreferably 10% to 70%.

When the content of content ofGd₂O₃+Ga₂O₃+Y₂O₃+Yb₂O₃+ZrO₂+TiO₂+Nb₂O₅+Ta₂O₅+WO₃ is too large,vitrification is difficult. When two or more selected from Gd₂O₃, Ga₂O₃,Y₂O₃, Yb₂O₃, ZrO₂, TiO₂, Nb₂O₅, Ta₂O₅, and WO₃ are contained, the totalamount is also preferably within the above range.

Hereinafter, each component Gd₂O₃, Ga₂O₃, Y₂O₃, Yb₂O₃, ZrO₂, TiO₂,Nb₂O₅, Ta₂O₅, and WO₃ will be described in detail.

Gd₂O₃ is a component that increases the refractive index. In addition,Gd₂O₃ also has an effect of improving weather resistance. However, whenthe content of Gd₂O₃ is too large, vitrification is difficult.Therefore, the content of Gd₂O₃ is preferably 0% to 45%, 0.1% to 40%, 1%to 35%, 3% to 30%, and particularly preferably 5% to 20%.

Ga₂O₃ is a component that increases the refractive index. In addition,since Ga₂O₃, as an intermediate oxide, forms a network of a glass, Ga₂O₃has an effect of expanding the vitrification range. However, when thecontent of Ga₂O₃ is too large, vitrification is difficult, and the costof raw materials tends to be high. Therefore, the content of Ga₂O₃ ispreferably 0% to 50%, 5% to 40%, 10% to 35%, and particularly preferably15% to 30%. When the cost of raw materials is prioritized, the contentof Ga₂O₃ is preferably 0% to 30%, 0% to 20%, and particularly preferably0% to 10%.

Y₂O₃ is a component that increases the refractive index. In addition,since Y₂O₃, as an intermediate oxide, forms a network of a glass, Y₂O₃has an effect of expanding the vitrification range. However, when thecontent of Y₂O₃ is too large, vitrification is difficult. Therefore, thecontent of Y₂O₃ is preferably 0% to 50%, 0% to 30%, 0% to 20%, andparticularly preferably 0% to 10%.

Yb₂O₃ is a component that increases the refractive index. However, whenthe content of Yb₂O₃ is too large, vitrification is difficult.Therefore, the content of Yb₂O₃ is preferably 0% to 50%, 0% to 30%, 0%to 20%, and particularly preferably 0% to 10%.

ZrO₂ is a component that increases the refractive index. In addition,since ZrO₂, as an intermediate oxide, forms a network of a glass, ZrO₂has an effect of expanding the vitrification range. However, when thecontent of ZrO₂ is too large, vitrification is difficult and the meltingtemperature becomes too high. Therefore, the content of ZrO₂ ispreferably 0% to 40%, 0.1% to 35%, 1% to 30%, 3% to 25%, andparticularly preferably 5% to 20%.

TiO₂ is a component that has a large effect of increasing the refractiveindex, and also has an effect of increasing chemical durability. Inaddition, TiO₂ also has an effect of reducing the Abbe number andincreasing the dispersion. The content of TiO₂ is preferably 0% to 85%,0.1% to 83%, 5% to 80%, and particularly preferably 10% to 75%. When thecontent of TiO₂ is too large, the absorption end shifts to the longwavelength side, so that the transmittance of visible light(particularly visible light in the short wavelength region) tends todecrease, and vitrification is difficult.

Nb₂O₅ is a component that has a large effect of increasing therefractive index, and is a component that reduces the Abbe number toincrease the dispersion. Nb₂O₅ also has the effect of expanding thevitrification range. The content of Nb₂O₅ is preferably 0% to 85%, 0.5%to 75%, 1% to 73%, and particularly preferably 2% to 70%. When thecontent of Nb₂O₅ is too large, vitrification is difficult.

Ta₂O₅ is a component that has a great effect of increasing therefractive index. However, when the content of Ta₂O₅ is too large,vitrification is difficult, and the cost of raw materials tends to behigh. Therefore, the content of Ta₂O₅ is preferably 0% to 60%, 0% to50%, 0% to 45%, and particularly preferably 0.1% to 40%.

WO₃ is a component that increases the refractive index. In addition,since WO₃, as an intermediate oxide, forms a network of a glass, WO₃ hasan effect of expanding the vitrification range. However, when thecontent of WO₃ is too large, vitrification is difficult. Therefore, thecontent of WO₃ is preferably 0% to 50%, 0% to 30%, 0% to 20%, andparticularly preferably 0% to 10%.

MgO, CaO, SrO and BaO are components that expand the vitrificationrange. The content of MgO+CaO+SrO+BaO is 0% to 15%, and preferably 0% to10%. When the content of MgO+CaO+SrO+BaO is too large, the refractiveindex decreases, making it difficult to obtain desired opticalproperties.

ZnO is a component that expands the vitrification range, and has theeffect of enhancing the thermal stability of the glass. The content ofZnO is 0% to 35%, and preferably 0% to 30%. When the content of ZnO istoo large, the refractive index decreases, making it difficult to obtaindesired optical properties.

CuO is a blue coloring component, and when contained in the glass acolor tone of vivid neon blue or neon green is provided. The content ofCuO is preferably more than 0% to 5%, 0.01% to 3%, 0.05% to 2%, andparticularly preferably 0.1% to 1%. When the content of CuO is toolarge, the coloring of the glass is increased. In the present invention,the content of CuO indicates all Cu components contained in the glass interms of CuO. It is preferable that Cu in the glass is in the state ofsix-coordinate Cu²⁺. When Cu⁺ increases in the glass, blue coloringbecomes light, and when four-coordinate Cu²⁺ increases, the glassbecomes brown and it is difficult to obtain a glass with neon blue. Inparticular, in a glass containing a large amount of high refractiveindex components such as TiO₂ and Nb₂O₅, the tendency thatfour-coordinate Cu²⁺ increases is remarkable. Therefore, the proportionof six-coordinate Cu²⁺ to all Cu in the glass is preferably 80 mol % ormore, and particularly preferably 90 mol % or more.

When the glass article according to the present invention positivelycontains components that expand the vitrification range, such as La₂O₃,Nb₂O₅, and B₂O₃, it is easy to prevent unreasonable crystallizationduring glass production and to increase the size of the glass article(for example, for diameter, 2 mm or more, 3 mm or more, 4 mm or more, 5mm or more, and particularly 6 mm or more).

The glass article according to the present invention may contain thefollowing components in addition to the above components.

P₂O₅ is a component that forms a network of a glass and expands thevitrification range. However, when the content of P₂O₅ is too large, therefractive index decreases, making it difficult to obtain desiredoptical properties. Therefore, the content of P₂O₅ is preferably 0% to20%, 0% to 15%, and particularly preferably 0% to 10%.

Li₂O, Na₂O, and K₂O are components that expand the vitrification range.However, when the content of Li₂O+Na₂O+K₂O is too large, the refractiveindex decreases, making it difficult to obtain desired opticalproperties, and the weather resistance decreases. Therefore, the contentof Li₂O+Na₂O+K₂O is preferably 0% to 20%, 0% to 15%, and particularlypreferably 0% to 10%. It is preferable that the content of eachcomponent Li₂O, Na₂O, and K₂O is also within the above range.

Bi₂O₃ is a component that increases the refractive index. However, whenthe content of Bi₂O₃ is too large, the glass is colored with yellow orred, it is difficult to obtain a glass with a desired color tone.Therefore, the content of Bi₂O₃ is preferably 0% to 20%, 0% to 15%, 0%to 10%, 0% to 5%, 0% to 1%, and most preferably Bi₂O₃ is substantiallynot contained. Here, the expression “is substantially not contained”means not intentionally contained in the raw material, and does notexclude the inclusion of unavoidable impurities. Objectively, it meansthat the content is less than 0.1%.

When a coloring component composed of an oxide of V, Cr, Mn, Fe, Co, Ni,Mo, Ru, Ce, Pr or Er is contained, the glass article can be adjusted toa desired color tone. These coloring components may be used alone or incombination of two or more thereof. The content of these oxides (thetotal amount when two or more types are contained) is preferably 0% to20%, 0.001% to 10%, 0.005% to 5%, and particularly preferably 0.01% to1%. Depending on the components contained, the coloring may become toostrong, the visible light transmittance may decrease, and the desiredbrilliance or fire may not be obtained. In this case, the content of theoxide may be less than 1%, 0.5% or less, and 0.1% or less.

The glass article according to the present invention preferably has arefractive index (nd) of 1.7 or more, 1.8 or more, 1.9 or more, 1.95 ormore, and particularly preferably 2.0 or more. Accordingly, thedifference in refractive index between the inside and the outside(atmosphere) of the glass article is large, and light is easilyreflected inside the glass article. As a result, it is easy to obtainsufficient brilliance as a decorative glass article. The upper limit ofthe refractive index is not particularly limited. When the upper limitthereof is too large, vitrification becomes unstable, so that the upperlimit is preferably 2.6 or less, 2.5 or less, and particularlypreferably 2.4 or less.

The glass article according to the present invention preferably has anAbbe number (vd) of 50 or less, 45 or less, and particularly preferably43 or less. Accordingly, the glass article is highly dispersed, and fireis likely to exhibit. The lower limit of the Abbe number is notparticularly limited. When the lower limit thereof is too small,vitrification becomes unstable, so that the lower limit is preferably 10or more, and particularly preferably 15 or more.

The glass article according to the present invention can be used fordecoration purposes such as jewelry, works of art, and tableware. Forexample, the glass article according to the present invention can beattached to decorations (jewelry) such as a ring, a pendant, an earring,or a bracelet as artificial jewels. The shape of the decorative glassarticle is not particularly limited, and examples thereof include aspherical shape, an elliptical shape, and a polyhedron.

The glass article according to the present invention is preferablysubjected to chamfering with so-called brilliant cut, step cut, mixedcut, and the like. Accordingly, light is easily reflected inside theglass article, and it is possible to enhance the brilliance, so that theglass article according to the present invention is particularlysuitable as an artificial jewel.

EXAMPLES

Hereinafter, the glass article according to the present invention willbe described in detail with reference to Examples, but the presentinvention is not limited to the following Examples.

Tables 1 to 4 show Examples (Nos. 1 to 36) and Comparative Examples(Nos. 37 to 39) of the present invention.

TABLE 1 mol % No. 1 No. 2 No. 3 No. 4 No. 5 No. 6 No. 7 No. 8 No. 9 No.10 La₂O₃ 40.36 26.97 32.96 26.93 26.97 37.92 35.36 26.97 34.96 34.96B₂O₃ 32.96 36.96 32.96 32.92 32.96 18.96 29.47 34.96 21.98 21.98 Al₂O₃0.1 0.2 1 4 SiO₂ 4 4 3.99 9.98 10.89 4 4 4 Gd₂O₃ 11.49 11.49 5 10.9711.69 14.97 15.48 11.49 13.99 9.99 Ga₂O₃ Yb₂O₃ 2 ZrO₂ 8.99 8.99 10.999.07 8.99 8.99 6.99 6.99 TiO₂ Nb₂O₅ 2 1.9 1.9 1.9 6.99 1.5 2.1 2 2 Ta₂Os11.39 10.99 11.97 11.39 10.98 7.2 11.39 15.98 19.98 WO₃ 2 Li₂O BaO 2 ZnO2 CuO 0.1 0. .1 0.1 0.1 0.1 0.2 0.1 0.1 0.1 0.1 Fe₂O₃ 0.15 B₂O₃ + 37.0637.16 37.96 36.91 36.96 28.94 40.36 38.96 25.98 25.98 Al₂O₃ + SiO₂Gd₂O₃ + 22.48 33.77 26.98 35.91 35.97 32.94 24.18 33.97 38.96 38.96Ga₂O₃ + Y₂O₃ + Yb₂O₃ + ZrO₂ + TiO₂ + Nb₂O₅ + Ta₂O₅ + WO₃ MgO + CaO + 0 20 0 0 0 0 0 0 0 SrO + BaO Refractive 1.91 1.95 1.95 1.96 1.95 2.00 1.931.95 2.01 2.02 index nd Abbe 40.9 37.5 37.4 36.5 37.9 34.6 40.0 37.334.8 34.1 number vd Color tone Neon Neon Neon Neon Neon Neon Neon NeonNeon Neon blue blue blue blue blue green blue green blue greenBrilliance A A A A A A A A A A Fire A A A A A A A A A A

TABLE 2 mol % No. 11 No. 12 No. 13 No. 14 No. 15 No. 16 No. 17 No. 18No. 19 No. 20 La₂O₃ 34.96 34.97 8.68 11.89 29.93 29.97 19.94 14.99 49.8559.85 B₂O₃ 21.98 21.98 35.2 24.27 69.82 19.94 29.97 29.91 29.93 Al₂O₃69.93 SiO₂ 4 4 8.68 15.08 Gd₂O₃ 9.99 9.99 2.99 4.5 Ga₂O₃ Yb₂O₃ ZrO₂10.99 6.99 5.59 6.59 TiO₂ 29.91 24.97 Nb₂O₅ 2 5.99 2.69 1.3 29.91 29.9719.94 9.98 Ta₂Os 15.98 15.98 2 4. 7 WO₃ 1.2 Li₂O 5.19 3 BaO ZnO 27.5328.57 CuO 0.1 0.1 0.15 0.1 0.1 0.1 0.3 0.1 0.3 0.25 Fe₂O₃ 0.1 0.15B₂O₃ + 25.98 25.98 43.88 39.35 69.82 69.93 19.94 29.97 29.91 29.93Al₂O₃ + SiO₂ Gd₂O₃ + 38.96 38.95 14.47 17.09 0 0 59.82 54.94 19.94 9.98Ga₂O₃ + Y₂O₃ + Yb₂O₃ + ZrO₂ + TiO₂ + Nb₂O₅ + Ta₂O₅ + WO₃ MgO + CaO + 0 00 0 0 0 0 0 0 0 SrO + BaO Refractive 2.00 2.02 1.81 1.85 1.77 1.77 2.222.14 2.04 1.98 index nd Abbe 35.1 33.4 40.9 40.1 50.0 44.8 19.8 19.930.6 34.4 number vd Color tone Neon Neon Neon Neon Neon Neon Neon NeonNeon Neon blue green blue blue blue blue green green blue blueBrilliance A A B B B B A A A A Fire A A B B B B A A A A

TABLE 3 mol % No. 21 No. 22 No. 23 No. 24 No. 25 No. 26 No. 27 No. 28No. 29 No. 30 La₂O₃ 39.88 49.93 39.9 49.88 29.91 29.91 39.92 49.95 39.9239.76 B₂O₃ 29.91 29.95 10 14.97 39.76 Al₂O₃ 29.94 SiO₂ Gd₂O₃ Ga₂O₃ 19.929.95 49.85 29.91 14.97 19.98 Yb₂O₃ ZrO₂ TiO₂ Nb₂O₅ 29.9 19.96 Ta₂Os29.91 19.97 19.94 39.88 29.94 29.97 29.94 19.88 WO₃ Li₂O BaO ZnO CuO 0.30.15 0.3 0.2 0.3 0.3 0.2 0.1 0.2 0.6 Fe₂O₃ B₂O₃ + 29.91 29.95 10 0 0 014.97 0 29.94 39.76 Al₂O₃ + SiO₂ Gd₂O₃ + 29.91 19.97 49.8 49.91 69.7969.79 44.91 49.95 29.94 19.88 Ga₂O₃ + Y₂O₃ + Yb₂O₃ + ZrO₂ + TiO₂ +Nb₂O₅ + Ta₂O₅ + WO₃ MgO + CaO + 0 0 0 0 0 0 0 0 0 0 SrO + BaO Refractive1.99 2.02 2.07 2.06 2.02 2.08 2.04 2.07 2.01 1.94 index nd Abbe 34.130.7 26.9 28.8 32.4 29.2 31.9 31.3 33.4 37.6 number vd Color tone NeonNeon Neon Neon Neon Neon Neon Neon Neon Neon blue blue green blue blueblue blue blue green blue Brilliance A A A A A A A A A A Fire A A A A AA A A A A

TABLE 4 mol % No. 31 No. 32 No. 33 No. 34 No. 35 No. 36 No. 37 No. 38No. 39 La₂O₃ 39.82 34.9 34.89 39.82 39.88 34.9 1.6 35 25.6 B₂O₃ 49.7749.84 39.88 44.8 39.88 24.93 4.89 22 33.2 Al₂O₃ 2.59 SiO₂ 50.27 4 3.8Gd₂O₃ 14 10.9 Ga₂O₃ 9.97 4.99 19.94 Yb₂O₃ ZrO₂ 1.9 7 8.5 TiO₂ Nb₂O₅ 2 2Ta₂Os 9.96 14.96 14.96 14.93 14.95 19.94 16 10.8 WO₃ Li₂O 15.16 Na₂O4.59 CaO 9.98 SrO 5.29 BaO 3.49 ZnO CuO 0.45 0.3 0.3 0.45 0.3 0.3 0.155.2 Fe₂O₃ 0.1 B₂O₃ + 49.77 49.84 39.88 44.8 39.88 24.93 57.75 26 36.97Al₂O₃ + SiO₂ Gd₂O₃ + 9.96 14.96 24.93 14.93 19.94 39.88 1.9 39 32.2Ga₂O₃ + Y₂O₃ + Yb₂O₃ + ZrO₂ + TiO₂ + Nb₂O₅ + Ta₂O₅ + WO₃ MgO + CaO + 0 00 0 0 0 18.76 0 0 SrO + BaO Refractive 1.91 1.92 1.94 1.95 1.95 1.981.61 2.01 Not index nd measured Abbe 40.2 38.3 37.7 36.9 36.6 34.8 55.634.8 Not number vd measured Color tone Neon Neon Neon Neon Neon NeonNeon Colorless Black blue blue blue blue blue blue blue Brilliance A A AA A A C A C Fire A A A A A A C A C

First, raw materials were mixed so as to have each glass compositionshown in the tables to prepare a raw material batch. The obtained rawmaterial batch was melted to be homogeneous, and then rapidly cooled toobtain a glass sample. The obtained glass sample was homogeneous and nodefects such as cracks were observed on the surface. The meltingtemperature was set to 1400° C. to 1700° C. The obtained glass samplewas annealed near the glass transition temperature (650° C. to 850° C.),and then the refractive index (nd) and the Abbe number (vd) weremeasured and the appearance (change in color tone, brilliance, fire) wasevaluated according to the following methods.

The right-angle polishing was performed on the glass sample and therefractive index (nd) and the Abbe number (vd) were measured by using aprecision refractometer (KPR-2000, manufactured by ShimadzuCorporation). The refractive index was evaluated by a measured valuewith respect to the d line (587.6 nm) of the helium lamp. The Abbenumber was calculated according to the equation Abbe number(vd)={(nd−1)/(nF−nC)} using values of the refractive index of the d lineand the refractive index of the F line (486.1 nm) and the C line (656.3nm) of the hydrogen lamp.

The appearance was evaluated as follows. First, brilliant cut processingwas performed such that the plane shape of each sample had a size ofabout 5 mm to 7 mm in diameter. The processed glass sample was visuallyevaluated for brilliance and fire under a fluorescent light source. Theevaluation was performed in the following four stages. Plane photographsof the sample Nos. 8, 9 and 39 are shown in FIG. 1 .

[Brilliance]

-   -   A: the sample looks bright and has strong brilliance.    -   B: the sample looks bright.    -   C: the sample has no brilliance (similar to a glass window).

[Fire]

-   -   A: the sample shows iridescent (various colors) brilliance.    -   B: the sample shows iridescent brilliance, but the number of        colors is small.    -   C: the sample has almost no iridescent brilliance.

As is clear from Table 1, sample Nos. 1 to 36 which are Examples show acolor tone with vivid neon blue or neon green, the brilliance is A, andthe fire is B or A, which are good. On the other hand, sample No. 37which is Comparative Example has a low refractive index of 1.61, a largeAbbe number of 55.6, and C for the brilliance and the fire because ofcontaining SiO₂ and MgO+CaO+SrO+BaO in large contents. Sample No. 38 iscolorless because of not containing CuO. Sample No. 39 has a too darkcolor as black because of containing CuO in a too large content.

1: A glass article comprising: in mol %, more than 0% to 70% of La₂O₃,0% to 80% of B₂O₃, 0% to 40% of SiO₂, 0% to 80% of B₂O₃+Al₂O₃+SiO₂, 0%to 85% of Gd₂O₃+Ga₂O₃+Y₂O₃+Yb₂O₃+ZrO₂+TiO₂+Nb₂O₅+Ta₂O₅+WO₃, 0% to 15% ofMgO+CaO+SrO+BaO, 0% to 35% of ZnO, and more than 0% to 5% of CuO. 2: Theglass article according to claim 1 comprising: in mol %, more than 0% to80% of B₂O₃+Al₂O₃+SiO₂. 3: The glass article according to claim 1comprising: in mol %, more than 0% to 85% ofGd₂O₃+Ga₂O₃+Y₂O₃+Yb₂O₃+ZrO₂+TiO₂+Nb₂O₅+Ta₂O₅+WO₃. 4: The glass articleaccording to claim 1, further comprising: a coloring component composedof an oxide of V, Cr, Mn, Fe, Co, Ni, Mo, Ru, Ce, Pr or Er in an amountof 0% to 20% in mol %. 5: The glass article according to claim 1, whichhas a refractive index of 1.7 or more. 6: The glass article according toclaim 1, which has an Abbe number of 50 or less. 7: The glass articleaccording to claim 1, which is subjected to chamfering. 8: The glassarticle according to claim 1, which is used for decoration. 9: The glassarticle according to claim 8, which is an artificial jewel. 10: Adecoration comprising: the glass article according to claim 8.